1. Field of the Invention
The present invention relates to a printer that discharges a sheet of paper having continuous pages to a postprocessor that disconnects this paper into sheets of paper in page units, and stores the disconnected sheets of paper in a stack. Particularly, the invention relates to a printer that switches print sides of the sheets based on presence or absence of an inversion mechanism that inverts the front and back sides of the sheets in the postprocessor.
2. Description of the Related Art
There are printers that can print on both sides of a sheet of paper having continues pages. The sheet of paper printed by the printer is stored into a body stacker that is incorporated in the printer main body or into a stacker of a postprocessor (for example, a Burster Trimmer Stacker) (hereinafter referred to as a “BTS stacker”) that receives the sheet of paper discharged from the printer, disconnects the printed paper into sheets of paper in page units by cutting or by bursting, and stores the disconnected sheets of paper in a stack.
FIG. 7 is a view showing the storage of paper. A printer 1 has a lever 2 that selects a stacker which stores a printed sheet of paper. FIG. 7A illustrates that the lever 2 selects a body stacker 3 that is incorporated in the printer 1. The printed sheet of paper is folded in page units, and is stored into the body stacker 3. On the other hand, FIG. 7B illustrates that the lever 2 selects a BTS stacker 6 of a postprocessor 5. The sheet or paper printed by the printer 1 enters the postprocessor 5 from a vent 4 of the printer. A disconnection mechanism not shown disconnects the sheet of paper into sheets of paper in page units, and stores the disconnected paper in a stack in the BTS stacker 6.
When sheets of paper printed on both sides of the paper are stored into the BTS stacker 6 of the postprocessor 5, the following problems arise.
FIG. 8 is a view showing a page layout of a two-side printed sheet of paper that is discharged from the printer. A first front side of the printed sheet of paper is the first page, and a back side of this paper is the second page. A front side that continues after the first page is the third page. A back side that continues after the second page is the fourth page. In other words, odd pages appear on the front side, and even pages appear on the back side of the paper. Therefore, in this page layout, the printed sheet of paper enters the postprocessor 5, and is disconnected into sheets of paper in page units. As shown in FIG. 8A, the disconnected sheets of paper are stacked on the BTS stacker 6, with page numbers appearing in the order of 2, 1, 4, 3, 6, 5, and so on from the bottom. Consequently, the page numbers are not continuous.
On the other hand, some postprocessor 5 has an inversion mechanism that inverts the front and back sides of the sheets of paper that are discharged from the printer. When the inversion mechanism is used, the page layout is reverse of the above, with the front side being an even page and the back side being an odd page, as shown in FIG. 8B. Therefore, when the sheet of paper is disconnected into sheets of paper in page units, and the disconnected sheets of paper are stacked on the BTS stacker 6, the page numbers appear as 1, 2, 3, 4, 5, and so on in this order from the bottom. Consequently, the page numbers are continuous in good order.
As explained above, when the postprocessor 5 has the inversion mechanism, the printed sheets of paper are stored in the BTS stacker 6 in a state in which the page numbers are continuous. However, when the postprocessor 5 does not have the inversion mechanism (that is, when the printed sheet of paper enters the postprocessor 5 in a state of being discharged from the printer 1, and when the paper disconnected into sheets of paper in page units are stored), the printed sheets of paper are stacked on the BTS stacker 6 in a state in which the page numbers are not continuous.